UNIVERSITY  OF   CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL    EXPERIMENT    STATION 

BERKELEY,    CALIFORNIA 


MANUFACTURE  OF  ROQUEFORT  TYPE 
CHEESE  FROM  GOAT'S  MILK 


S.  A.  HALL  and  C.  A.  PHILLIPS 


BULLETIN  397 

November,  1925 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1925 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/manufactureofroq397hall 


MANUFACTURE  OF  ROQUEFORT  TYPE  CHEESE 
FROM  GOAT'S  MILK 


S.  A.  HALL*  and  C.  A.  PHILLIPS t 


The  milk  goats  in  California  produce  more  milk  than  the  present 
market  can  use  fresh.  Many  goat  farms  are  located  in  isolated 
places,  from  which  it  is  impracticable  to  ship  out  fresh  milk.  The 
result  is  an  unutilized  surplus.  The  manufacture  of  cheese  from 
goat's  milk  has  been  suggested  as  a  use  for  this  surplus,  and  experi- 
ments to  manufacture  cheese  of  Roquefort  type  have  been  made.  The 
Roquefort  cheese  process,  as  perfected  in  France,  employs  sheep's 
milk.  In  America,  a  similar  cheese  has  been  made  successfully  from 
cow's  milk  by  the  Bureau  of  Dairying  of  the  United  States  Depart- 
ment of  Agriculture.1  The  chief  defect  of  the  cow's  milk  cheese  is  its 
yellow  color,  due  to  the  large  amount  of  coloring  matter  in  the  milk. 
Goat's  milk,  which  is  similar  to  sheep's  milk  in  color  and  body,  pro- 
duces Roquefort  type  cheese  of  excellent  quality. 

CARE  OF  THE  MILK 

The  same  care  and  skill  necessary  in  the  production  of  clean  milk 
of  any  kind  should  be  used  when  producing  goat 's  milk  for  Roquefort 
cheese.  All  utensils,  buckets,  strainers,  coolers,  etc.,  should  be  thor- 
oughly cleansed  and  sterilized.  The  milking  sheds  should  be  kept 
clean  and  free  from  barnyard  dust.  The  flanks  and  udders  of  the 
goats  should  be  clean  at  the  time  of  milking.  Bucks  should  be  kept 
a  considerable  distance  from  the  milking  sheds  in  order  that  dis- 
agreeable odors  may  not  be  taken  up  by  the  milk.  The  evening  milk 
should  be  cooled  immediately  after  milking  to  50°-60°F.  and  held 
at  that  temperature  over  night.  Though  it  is  desirable  to  cool  the 
morning  milk  also,  cheese  of  satisfactory  quality  can  be  made  from 
the  warm  milk  if  it  is  used  within  two  or  three  hours  after  milking. 
In  this  case,  the  warm  morning  milk  should  be  brought  to  the  factory 
in  separate  cans  where  it  may  be  mixed  with  the  cool  evening  milk 
by  the  cheese  maker. 


*  Assistant    Dairy    Manufacturing    Specialist,    Bureau    of    Dairying,    United 
States  Department  of  Agriculture. 

t  Of  the  Division  of  Dairy  Industry. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


COMPOSITION  OF  COW'S,  SHEEP'S,  and  GOAT'S  MILK 

Goat's  milk,  unlike  sheep's  milk,  does  not  differ  greatly  in  per- 
centage composition  from  cow 's  milk. 

TABLE  1 

Average  Percentage  Composition  of  Milk 


Cow's  milk* 

Sheep's  milkf 

Goat's  milkf 

Water         

Per  cent 

87.27 
3.39 
3.68 
4.94 

.72 

Per  cent 

79.5 
6.5 
8.0 
4.5 
1.0 

Per  cent 

86.09 

Protein              

3.55 

Fat                 

4.79 

Sugar                    

4.85 

Ash      

.72 

*  Heineman,  P.  G.    Milk:  70.    1921. 

t  Matheson,  K.  J.    Manufacture  of  cow's-milk  Roquefort  cheese.    U.  S.  Dept.  Agr.  Bui.  970;  6.    1921- 

J'Voorhies,  E.  C.    The  milk  goat  in  California.    Calif.  Agri.  Exp.  Sta.  Bui.  285;  9.    1921. 

The  analysis  of  the  goat 's  milk  used  in  the  manufacture  of  Roque- 
fort type  cheese  at  the  University  Farm  showed  considerably  less 
total  solids  and  fat  than  is  given  in  table  1. 


COMPOSITION  OF  KOQUEFORT  CHEESE 

Table  2  shows  the  composition  of  several  samples  of  the  highest 
quality  Roquefort  cheese  analyzed  by  Dox.* 

TABLE  2 
Average  Percentage  Composition  of  Roquefort  Cheese 


Water 

Fat 

Protein 

Ash 

Salt 

Average  

Per  cent 

38.69 
37.49 
40.10 

Per  cent 

32.21 
31.50 
33.53 

Per  cent 

21.39 
19.14 
23.06 

Per  cent 

6.14 
5.18 
6.81 

Per  cent 

4.14 

Minimum  

3.64 

Maximum    

4.88 

The  results  of  analyses  of  goat's  milk  and  cow's  milk  Roquefort 
type  cheeses  made  in  our  experiments  are  shown  in  table  3. 

*  Matheson,  K.  J.    Manufacture  of  cow 's  milk  Eoquef ort  cheese.     U.  S.  Dept. 
Agr.  Bui.  970:3.     1921. 


Bull.  397 


ROQUEFORT    TYPE    CHEESE    FROM    GOAT  S    MILK 


TABLE   3 

Average  Percentage  Composition  of  Roquefort  Type  Cheese 


Water 


Fat 


Fat  in  dry- 
matter 


Salt 


Goat's  milk  Roquefort. 
Cows'  milk  Roquefort.. 


Per  cent 

43.78 
46.06 


Per  cent 

25.41 

27. 16 


Per  cent 

45.19 
50.35 


Per  cent 

5.38 
5.46 


THE  MANUFACTURE  OF  GOAT'S  MILK  ROQUEFORT  CHEESE 

In  the  manufacture  of  this  cheese  at  the  University  Farm,  the 
methods  outlined  in  France  by  Marre,2  and  in  this  country  by 
Matheson1  were  used  with  some  modifications. 

Acidity. — As  previously  stated,  fresh  clean  milk  is  necessary  for 
making  Roquefort  cheese.  The  acidity  should  be  between  .16  and  .18 
percent  for  the  best  results.  Over-ripe  milk  is  likely  to  result  in  a  gassy 
cheese  and  sometimes  an  objectionable  flavor.  From  3  to  4  per  cent 
of  good  clean  lactic  starter  should  be  used  according  to  the  acidity  of 
the  milk  and  starter. 

Temperature. — For  sheep's  milk  the  temperature  of  setting  used 
in  France  is  from  76°  to  84°F.  Cow's  milk  should  be  set  at  82°  to 
85°F.,  and  goat's  milk  at  82°F.  When  goat's  milk  was  set  above 
this  temperature,  difficulty  was  encountered  with  cracking  of  the 
curd.  When  2G  per  cent  of  cow's  milk  was  added  to  the  goat's 
milk  this  difficulty  was  overcome.  When  combinations  of  cow's  and 
goat's  milk  are  used,  it  is  advisable  to  set  the  milk  at  84°F.  A  lower 
temperature  is  liable  to  result  in  a  soft,  mushy  curd  which  fails  to 
drain  properly,  while  a  higher  temperature  may  result  in  a  tough 
curd. 

Setting  and  rennet. — The  milk  is  heated  in  an  ordinary  cheese 
vat  and  stirred  to  insure  even  distribution  of  fat  and  heat.  After 
the  acidity  has  developed  to  .21  or  .22  per  cent,  commercial  rennet 
diluted  from  twenty  to  forty  times  with  pure  cold  water  is  added 
to  the  milk,  which   is  then  agitated  thoroughly. 

Time  for  coagulation. — The  setting  period  should  be  approximately 
one  and  one-half  hours,  but  varies  with  the  acidity,  temperature,  and 
quality  of  the  milk.  At  first,  beads  of  whey,  then  a  film  of  whey, 
gradually  spreads  over  the  surface  of  the  curd,  indicating  that  it  is 


b  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

ready  to  cut.  The  curd  is  cut  two  ways  with  a  coarse,  vertical  knife 
with  wires  %  in.  to  1  in.  apart.  Soon  after  this,  the  curd  slowly 
contracts  and  draws  away  from  the  sides  of  the  vat.  This  contraction 
should  not  be  allowed  to  go  too  far,  however,  before  dipping  the 
curd. 

Draining  the  curd. — A  cheddar  cheese  vat  similar  in  capacity  to 
that  in  which  the  milk  was  set,  makes  an  excellent  drain  vat,  if  it  is 
provided  with  a  false  bottom  covered  with  cheese  cloth  or  muslin 
of  good  quality.    The  two  vats  should  be  placed  near  enough  together 


Fig.   1. — Sprinkling  mold  powder  between  layers   of  curd  in   the  hoops. 


to  permit  two  or  three  workers  to  do  the  dipping.  Large  tin  scoops, 
each  with  a  capacity  of  three  or  four  quarts,  are  suitable  for  this 
purpose. 

The  curd  should  be  transferred  to  the  drain  vat  rapidly  and  care- 
fully. Two  men  should  be  able  to  take  the  curd  from  1500  pounds 
of  milk  in  from  ten  to  fifteen  minutes. 

Raising  the  cloths  from  time  to  time  aids  in  expelling  the  whey 
and  in  bringing  the  draining  curd  to  the  proper  condition  of  dryness. 
The  time  required  for  draining  is  from  twenty  to  forty  minutes, 
according  to  how  often  the  clothes  are  raised  during  this  period. 
The  curd  should  be  placed  in  the  forms  in  a  fairly  moist  condition. 
When  it  is  too  dry,  the  surface  of  the  cheese  becomes  so  open  and 
rough,  that  undesirable  organisms  may  have  access  to  the  interior. 
Greater  losses  occur  in  the  curing  process  when  such  conditions 
exist. 


BULL.  397]  ROQUEFORT   TYPE   CHEESE   FROM    GOAT 's   MILK  7 

Butterfat  losses. — The  whey  should  be  drawn  from  the  drain  vat 
and  run  through  a  whey  separator.  The  average  fat  loss  from  goat's 
milk  is  from  0.50  to  0.60  per  cent,  while  that  from  cow's  milk  is  from 
0.20  to  0.30  per  cent.  When  20  per  cent  of  cow's  milk  is  added  to 
goat's  milk,  the  fat  loss  is  reduced  to  about  0.40  per  cent.  It  is 
probable  that  a  satisfactory  reduction  of  the  loss  would  be  obtained 
with  somewhat  less  than  20  per  cent  addition  of  cow 's  milk. 

Hooping  and  Inoculation. — The  hoops  (or  forms)  for  Roquefort 
cheese  are  made  of  galvanized  metal  with  wire  edges.  They  are  round 
and  open  on  both  ends,  and  are  seven  and  three-eighths  inches  in 
diameter  and  six  inches  high.  They  have  six  horizontal  rows  of  holes. 
Each  row  has  twenty-five  holes  one-eighth  inch  in  diameter.  The 
hoops  are  placed  upon  special  reed  mats,  ten  by  twenty-four  inches. 
The  mats  are  placed  upon  boards  of  approximately  the  same  size, 
each  of  which  will  hold  three  hoops.  Cloths  may  be  used  instead  of 
mats,  but  they  are  not  so  satisfactory.  All  hoops,  mats,  and  boards 
should  be  thoroughly  cleaned  and  sterilized  before  using,  to  reduce 
the  number  of  foreign  molds  which  may  appear  later. 

When  it  is  put  into  the  hoop,  the  curd  is  a  white,  pulpy  mass  and 
should  contain  only  a  small  excess  of  whey.  The  hoop  is  filled  with 
four  or  five  layers  of  curd,  between  which  liberal  applications  of  mold 
powder  are  sprinkled. 

Draining  the  cheese. — The  drain  room  should  have  a  temper- 
ature of  65°-68°F.  and  a  relative  humidity  of  85-90  per  cent  to 
prevent  the  cheese  from  drying  out.  Higher  temperatures  favor 
the  development  of  injurious  molds.  The  cheese  is  left  in  the  room 
about  four  days.  It  is  turned  several  times  during  the  first  day  and 
twice  daily  thereafter.  The  object  of  the  repeated  turnings  is  to 
hasten  drainage  and  to  insure  a  smooth,  even  surface.  The  hoops, 
which  are  allowed  to  remain  around  the  cheese  for  the  first  one  or 
two  days,  should  be  washed  and  sterilized  before  using  again.  The 
boards  should  be  washed  every  day.  The  cheese  is  scraped  each  day 
while  in  the  drain  room  in  order  to  remove  the  coating  of  slime  which 
forms  over  the  surfaces. 

Salting. — The  salting  room  should  be  dry  and  should  have  a  tem- 
perature of  approximately  48 °F.  There  should  be  sufficient  ven- 
tilation to  remove  the  excess  of  moisture  drawn  to  the  surface  of  the 
cheese  by  the  salt. 

The  cheese  should  be  salted  two  or  three  times  at  two-day  intervals, 
according  to  the  amount  of  salt  desired  and  the  conditions  affecting 
its  penetration.  The  cheese  should  be  placed  in  the  salting  room  sev- 
eral hours  before  the  first  salt  is  applied,  in  order  to  cool  it  to  the 


s 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


temperature  of   the  room.     Cheese   salt  is  then  rubbed  vigorously 
over  the  surface,  until  no  more  will  adhere. 

After  the   cheeses  are  thus  salted,  they  are   piled  two  or  three 
high,  and  the  following  day  their  positions  reversed,  with  no  addition 


Fig.   2. — The   drain  room,  where   the   cheese  remains   four   or  five   days. 


of  salt.  On  the  third  day  they  are  again  salted  in  the  manner  pre- 
viously described.  On  the  fifth  day  they  may  receive  a  light  sprink- 
ling of  salt  for  markets  preferring  a  highly  salted  cheese. 

The  salting  period  should  be  from  ten  to  fourteen  days,  according 
to  the  condition  of  the  cheese. 


Bull.  397 


ROQUEFORT    TYPE   CHEESE   FROM    GOAT  S    MILK 


Some  experience  is  required  to  salt  Roquefort  cheese  successfully, 
the  usual  tendency  being  to  undersalt  or  to  oversalt.  Cured  Roque- 
fort cheese  should  contain  at  least  4  per  cent  of  salt,  an  amount  which 
is  sufficient  to  prevent  an  excessive  development  of  the  mold,  Oidium 
lactis.    Most  of  the  cheese  made  in  these  experiments  contained  from 


Fig.  3. — A  truck  for  transporting  cheese  from  the  drain  room  to  the  salting  room. 


5  to  6  per  cent,  which  did  not  seem  to  injure  the  quality  for  most  of 
the  consumers,  although  some  preferred  less. 

Scraping. — During  the  salting  process  a  slimy  coat,  composed  of 
softened  cheese,  whey,  salt,  and  micro-organisms,  begins  to  form.  This 
coating  is  scraped  off  with  an  ordinary  case  knife.  Care  should  be 
taken  not  to  scrape  the  cheese  too  deeply,  since,  at  this  period,  a  high 
percentage  of  salt  in  the  surface  is  essential. 


10 


UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 


Punching. — The  cheese  is  punched  immediately  after  the  scraping. 
Oxygen  is  necessary  for  the  proper  growth  of  the  Roquefort  mold,  and 
in  order  to  let  the  air  in,  each  cheese  is  punched  with  a  needle  in 
twenty  to  fifty  places.  The  needles  are  about  one-eighth  inch  in 
diameter  and  about  eight  inches  long.  The  cheese  is  placed  on  edge 
after  the  punching  in  order  that  the  holes  may  not  be  closed,  and  that 
the  maximum  amount  of  air  may  come  in  contact  with  the  mold. 


Fig.  4. — Punching  the  cheese  with  a  needle  to  permit  the  entrance  of  air. 

Ripening  or  curing. — The  curing  room  should  have  a  temperature 
of  42°-48°F.,  a  relatively  high  humidity  (about  92  per  cent),  and 
moderate  ventilation. 

TABLE  4 
Conditions  Favorable  for  Curing  Goat's-Milk  Koquefort  Cheese 


Period 

Temperature 

Relative 
humidity 

Ventilation 

First  four  days 

Degrees  F. 

65-68 
46-48 
42-48 
42-48 
42-48 
46-48 

Per  cent 

85-90 
80-90 
90-95 
90-95 
90-95 
80-90 

Slight 

Considerable 

Moderate 

Moderate 

Moderate 

Considerable 

Next  ten  days 

Third  week 

Fourth  and  fifth  weeks 

Second  and  third  months 

Fourth  and  fifth  months 

The  humidity  and  ventilation  indicated  in  table  4  cannot  be 
expressed  with  any  great  degree  of  accuracy  at  the  present  time.  The 
table  shows  in  a  general  way,  however,  the  conditions  that  have  proved 
most  successful.    With  experience,  they  can  be  controlled  properly. 


BULL.  397]  ROQUEFORT   TYPE   CHEESE   PROM    GOAT 's   MILK 


11 


Fig.  5. — The  cheese  placed  on  edge  on  the  curing  shelves. 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

Curing  rooms  for  Roquefort. — In  the  work  at  the  University  Farm, 
well-insulated  curing  rooms  were  used.  The  sides,  tops  and  bottoms 
were  insulated  with  four  inches  of  cork  laid  in  hot  asphalt  and  covered 
with  Portland  cement  plaster.  Direct  expansion  ammonia  refrigera- 
tion and  brine  coils  were  used  in  order  to  maintain  the  low  tempera- 
ture. A  perforated  water  pipe  was  placed  along  the  top  of  the  room 
so  that  water  could  trickle  down  over  a  screen  behind  the  shelves  in 
order  to  maintain  the  proper  humidity.  Water  cooled  to  room  tem- 
perature is  more  economical  than  tap  water,  since  the  cost  of  refriger- 
ation  is   lower.     A   vacuum   cleaner   motor   was   installed,   and  run 


Fig.  6. — A  vacuum  cleaner  motor  used  for  circulation  of  air  in  small  curing  rooms. 

continuously  at  low  speed,  in  order  to  obtain  the  proper  circulation 
of  air.  The  air  was  drawn  from  the  curing  room  and  forced  back 
again.    Outside  air  was  taken  in  only  when  the  door  was  open. 

During  the  first  two  or  three  weeks  there  should  be  a  gradual  devel- 
opment of  a  reddish  slime  upon  the  surface  of  the  cheese,  together 
with  patches  of  white  and  green  mold.  In  cases  where  the  reddish 
slime  fails  to  develop  rapidly,  scrapings  may  be  obtained  from  other 
cheese.  These,  mixed  with  sterile  water  and  then  sprinkled  on  the 
cheese,  give  the  desired  growth  without  difficulty.  This  growth  should 
be  removed  by  scraping  (see  fig.  7),  every  three  or  four  weeks  in  order 
to  permit  the  air  to  reach  the  mold  in  the  interior  of  the  cheese. 
After  this  scraping  there  is  only  a  slight  development  of  the  white  and 
green  mold,  but  there  is  much  greater  development  of  reddish  slime. 


BULL.  397]  ROQUEFORT   TYPE   CHEESE   FROM    GOAT 's   MILK  13 

Within  ten  days  after  punching-,  mold  can  be  seen  through  the 
punched  holes  when  the  cheese  is  held  before  an  electric  light.  Within 
two  or  three  weeks  or  a  month,  there  is  probably  as  much  green  mold 
visible  as  when  cheese  is  cut  several  months  later.  The  mold  in  the 
center  of  the  cheese  appears  to  develop  more  rapidly  than  that  nearer 
the  surface,  probably  because  of  the  difference  in  concentration  of 
salt.  In  the  earlier  stages  of  ripening,  the  cheese  often  tastes  bitter. 
Later  this  condition  disappears  and  a  sweet,  piquant  flavor  is  notice- 
able with  little  or  no  bitterness.  With  the  proper  curing  conditions, 
the  texture  of  goat's-milk  Roquefort  cheese  can  be  made  similar  to 
that  of  the  imported.  In  some  cheese,  in  these  experiments,  there  was 
a  typical  peppery  flavor,  often  repellent  to  the  taste.    This  is  probably 


Fig.  7. — Scraping  the  surface  of  the  cheese  with  a  case  knife. 

due  to  an  intense  oxidation  as  is  evidenced  by  the  formation  of  formic 
acid,  which  occurs  when  the  cheese  is  held  for  a  long  period  at  a  high 
temperature.1 

High  humidity  prevents  the  cheese  from  drying  and  increases  the 
rapidity  of  the  growth  of  the  slime  on  the  surface.  No  experimental 
data  is  available  to  show  that  the  surface  growth  aids  in  the  ripening 
of  the  cheese,  but  its  presence  is  always  associated  with  the 
best  grades.  This  slime  seems  to  check  the  growth  of  surface 
mold  and  to  keep  the  cheese  in  a  sweet,  normal  condition.  Dryness 
causes  the  cheese  to  ripen  slowly  with  a  flavor  lacking  the  character- 
istics of  good  Roquefort,  and  a  texture  which  is  too  waxy. 

The  cheese  may  be  taken  from  the  curing  shelves  when  about  three 
months  old,  scraped  for  the  last  time,  and  wrapped  in  tin  foil  or 
aluminum  foil.  At  this  time  there  should  be  an  abundance  of  mold 
and  some  flavor,  but  as  a  rule,  the  full  flavor  develops  only  after  the 
cheese  has  been  left  in  the  foil  for  a  few  months. 

Enclosing  in  the  foil  prevents  drying,  excessive  oxidation,  and  the 
escape  of  the  volatile  substances.  This  also  helps  to  develop  the  sweet 
flavor,  and  reduces  the  formation  of  strong,  biting,  and  soapy  flavors 


14  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

which  may  occur  when  cheese  is  exposed  too  long  to  the  air.  Parch- 
ment paper  is  used  to  protect  the  foil.  Paraffin  cannot  be  used  as  a 
substitute  for  foil  on  account  of  the  moist  condition  of  the  surface  of 
the  cheese.  It  will  not  protect  the  cheese  so  well  and  does  not  make  an 
attractive  appearance. 

Roquefort  cheese  from  goat's  milk  requires  from  four  to  seven 
months  to  ripen.  AVhen  ripened  it  may  be  placed  in  cold  storage  at 
about  34°F.  for  eight  months  to  one  year  in  order  that  a  uniform 
supply  of  cheese  may  be  placed  on  the  market  throughout  the  year. 
During  this  storage,  the  cheese  should  become  sweeter  and  more  fra- 
grant. 


Fig.  8. — Wrapping  the  cheese  in  foil  and  parchment  paper. 

Losses  in  curing. — In  Roquefort  cheese,  made  from  cow's  milk,  the 
average  loss  from  scraping,  brushing  and  handling  is  7.4  per  cent, 
which  seems  to  be  less  than  the  loss  in  sheep 's  milk  Roquefort.1  The 
losses  in  goat 's  milk  Roquefort  in  our  work  were  very  small  on  account 
of  the  firmness  of  the  cheese. 

The  loss  from  shrinkage  will  vary,  according  to  the  moisture  con- 
tent of  the  cheese  at  the  time  it  is  wrapped  in  foil,  the  temperature, 
and  the  time  held  before  shipment.  Even  under  the  best  conditions, 
there  is  some  shrinkage  due  largely  to  evaporation  and  leakage  of 
whey. 

Yield. — Goat's  milk  with  an  average  butterfat  content  of  3.4  per 
cent  was  used  and  gave  an  average  yield  of  10.34  pounds  of  cheese  for 
each  100  pounds  of  milk. 

Preparation  of  mold  powder. — Mold  powder  for  inoculation  pur- 
poses is  grown  on  ordinary  white  bread.  Stock  cultures  of  Roquefort 
mold  should  be  obtained  from  a  reliable  laboratory  several  weeks 
before  the  manufacture  of  cheese  is  contemplated. 


BULL.  397]  ROQUEFORT   TYPE   CHEESE   FROM    GOAT 's   MILK 


15 


The  mold  powder  is  prepared  as  follows.  Fresh  loaves  of  bread 
are  sterilized  by  heating  in  a  drying-  oven  for  two  hours  at  170°  C. 
(338°F.)-  They  are  then  cooled  to  room  temperature.  In  the  mean- 
while, a  suspension  of  mold  is  made  by  transferring  spores  from  an 
agar  culture  of  Roquefort  mold,  by  means  of  a  sterile  platinum 
needle,  to  a  flask  of  sterile  water  and  shaking. 


Fig.  9. — Inoculating  bread  with  a  pure  culture  of  Eoquefort  mold. 


A  sterilized  (1  c.c.)  pipette  is  then  filled  with  this  suspension  and 
the  bread  inoculated  by  allowing  a  small  quantity  of  the  suspension 
to  flow  into  numerous  holes  previously  punched  with  a  sterile  glass  rod 
or  a  sterile  pipette  (see  fig.  9).  At  least  one  ounce  of  the  suspension 
should  be  used  for  each  pound  of  bread  and  the  punctures  well  dis- 
tributed to  insure  an  abundant  growth  of  mold  in  all  parts  of  the 
loaf.  The  inoculated  bread  is  put  into  a  moist  cold  place  (48°F.)  and 
left  for  several  weeks  to  allow  the  mold  to  develop  to  the  stage  suit- 
able for  use  in  the  cheese.  This  stage  is  indicated  by  the  spreading 
of  the  green  mold  throughout  the  bread. 

The  Roquefort  mold  develops  more  vigorously  in  the  cheese  and  is 
less  likely  to  be  contaminated  with  foreign  molds  when  grown  at  a 
low  temperature.  When  there  is  evidence  of  foreign  mold  in  the 
bread,  either  the  infected  part  should  be  removed  or  the  entire  loaf 


16 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


discarded.  Since  Roquefort  mold  grows  rapidly  at  a  low  temperature 
in  the  presence  of  carbon  dioxide  gas,  foreign  molds  cause  but  little 
trouble  in  the  cheese.  This  is  especially  true  with  Roquefort  mold 
grown  in  bread  at  a  temperature  of  48  °F. 

When  the  bread  is  completely  invaded  by  the  mold  it  is  thoroughly 
dried  and  then  sliced  and  ground  in  a  coffee  grinder  or  with  a  rolling 
pin  fine  enough  to  pass  through  a  salt  shaker.  It  should  be  kept  in 
a  cool  dry  place  to  prevent  the  absorption  of  moisture.  Before  drying, 
the  mold  in  bread  is  light  green,  but  upon  drying  it  darkens.  It  will 
keep  for  several  months  in  a  dark,  dry  place. 


Fig.  10. — Eoquefort  cheese  packed  in  excelsior,  sawdust  or  shavings. 


Methods  of  packing. — Roquefort  cheese  is  marketed  in  wooden 
boxes,  either  pine,  white-fir,  or  spruce,  holding  three,  six  or  twelve 
cheeses  each.  The  twelve-cheese  boxes  are  8  in.  by  8  in.  by  3  feet  9  in., 
inside  dimensions.  They  are  divided  into  three  or  four  compartments  to 
hold  three  or  four  cheeses  each.  The  sides,  top,  and  bottom,  are  %  in. 
thick,  and  the  ends  and  compartment  pieces  1:J^6  in.  thick.  The  six 
and  three-cheese  boxes  are  made  proportionally  smaller  from  similar 
material  (fig.  10). 

The  cheese  is  covered  with  foil  which  should  be  wrapped  neatly  and 
securely  about  it.  The  dimensions  of  the  foil  are  22  in.  by  13  in., 
and  there  are  from  eighteen  to  twenty-five  sheets  to  a  pound.  The 
foil  is  separated  from  the  cheese  by  a  layer  of  thin  paper  to  which 
it  is  attached.     Ordinarily,  the  trade  name  and  design  are  printed  in 


BULL.  397]  ROQUEFORT   TYPE   CHEESE   FROM    GOAT 's   MILK  17 

black  upon  the  foil.  When  the  cheeses  are  ready  to  ship,  they  are 
wrapped  in  strong  paper  and  tied  with  a  cord.  This  holds  them  in 
shape  and  gives  protection  in  transit.  The  net  weight  of  cheese  is 
marked  on  the  paper. 

The  wrapped  cheese  is  then  packed  in  sawdust,  pine  shavings,  or 
excelsior,  which  is  needed  to  absorb  any  leakage  brought  about  by  a 
change  from  low  to  high  temperatures.  No  difficulty  has  been  en- 
countered from  the  cheese  absorbing  odors  from  the  box  or  packing 
materials. 


Fig.  11. — Mold  growth  in  goat's  milk  Eoquefort  cheese  made  at  the 
University  Farm. 


POSSIBILITIES  FOE  GOAT'S-MILK  EOQUEFOKT  CHEESE 

The  making  of  goat's-milk  Roquefort  cheese  is  strictly  a  factory 
process,  and  should  not  be  attempted  either  on  the  farm  or  in  a  com- 
mercial plant  by  inexperienced  operators  or  where  equipment  for 
proper  curing  conditions  is  lacking.  We  recall  previous  efforts  to  make 
Roquefort  cheese  that  have  failed,  largely  because  these  factors  have 
not  received  proper  consideration. 

We  believe,  however,  that  there  is  a  great  future  for  goat's-milk 
Roquefort  cheese,  since  it  resembles  the  imported  article  so  closely. 
Cooperative  manufacturing,  if  properly  organized,  might  make  Cali- 
fornia just  as  famous  for  its  goat's-milk  Roquefort  cheese  as  Aveyron 
of  southern  France  is  for  its  sheep  's-milk  Roquefort. 

Because  of  the  excellent  quality  of  the  goat's-milk  cheese,  and  its 
resemblance  to  the  imported,  the  selling  price  of  the  two  has  been 
practically  the  same.  A  record  of  the  sales,  both  retail  and  wholesale, 
was  kept  and  sufficient  repeat  orders  were  received  to  make  it  safe  to 
conclude  that  the  cheese  was  satisfactory. 


18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


EQUIPMENT  FOR  ROQUEFORT  CHEESE   MANUFACTURE 

The  following  equipment  is  necessary,  in  addition  to  the  curing 
rooms  described  above,  for  a  factory  handling"  1500  pounds  of  milk 
daily : 

TABLE  5 
Equipment  for  Roquefort  Cheese  Manufacture 


Equipment 

Number 

Capacity  or  size 

Boiler...  .                   

1 

6 
1 
1 
1 

2 
2 

25 
1 
1 
1 
2 

75 
1 
1 
6 
1 
1 
1 
1 

5  horse  power 

Case  knives 

Cheese  vat  ... 

200  gallons 

Compressor 

5  tons 

Conductor  head 

Conductor  trough 

Curd  pails 

4  inches 
2  gallons 

Curd  scoops 

1  gallon 

Draining  mats... 

10  inches  by  24  inches 

Drain  vat 

200  gallons 

Hand  truck 

30  inches  bv  60  inches 

Hygrometer 

Wet  and  dry  bulb,  30°  to  140°  F. 

Punches 

8  inches 

Roquefort  hoops 

5  pounds 

Scales                          

1000  pounds 

Starter  can  .                     

20  gallons 

Thermometers 

20°  to  220°  F. 

Vertical  curd  knife 

8  inches 

Wash  sink 

2  feet  by  3  feet 

Weigh  can 

50  gallons 

Whey  separator 

1350  pounds 

In  addition  to  the  equipment  listed  (table  5)  the  following  sup- 
plies are  needed :  cheese  boxes,  drain  cloth,  mold  powder,  rennet,  salt, 
strainer  cloth,  lactic  starter,  tin  foil  or  aluminum  foil,  twine,  and 
wrapping  paper. 

COST  OF  MANUFACTURE 

The  figures  given  on  cost  of  manufacture  are  based  upon  milk  test- 
ing 3.67  per  cent  fat  and  costing  $2.16  for  100  pounds.  The  average 
yield  of  cheese  was  11.6  pounds  for  each  100  pounds  of  3.67  per  cent 
milk.  Part  of  this  cheese  was  made  from  goat's  milk,  part  from  cow's 
milk,  and  part  from  mixtures  of  the  two. 

The  labor  was  figured  as  one  man  to  each  1000  pounds  of  milk, 
and  the  cost  of  labor  at  $125  a  month  of  twenty-six  working  days. 
The  average  weight  of  a  cheese  was  4.87  pounds. 


BULK  397]  ROQUEFORT    TYPE    CHEESE    FROM    GOAT 's    MILK  19 

TABLE  6 
Estimated  Cost  of  Producing  Roquefort  Type  Cheese 

Cost  per 
Item  pound  cheese 

Cost  of  milk $0.2220 

Cost  of  refrigeration 0.0655 

Cost  of  water  and  steam 0.0010 

Cost  of  salt 0.0002 

Cost  of  rennet 0.0001 

Cost  of  labor 0.0415 

Cost  of  foil 0.0082 

Cost  of  wrapping  paper  and  string 0.0018 

Cost  of  boxes 0.0069 

Interest,  taxes,  insurance 0.0290 

Depreciation  on  building  and  equipment 0.0215 

Cost  of  electricity 0.0100 

Total  cost  per  pound $0.4077 

The  estimated  cost  of  producing  Roquefort  type  cheese  (table  6) 
will  vary  according  to  the  price  paid  for  the  milk  and  the  quantity 
of  cheese  manufactured.  It  is  not  the  desire  of  the  authors  to  recom- 
mend a  price  for  goat's  milk.  The  price  quoted  above  was  the  price 
"for  manufacturing  purposes"  paid  by  the  University  Farm  Cream- 
ery for  milk  containing  3.67  per  cent  of  butterfat.  Goat's-milk  Roque- 
fort cheese  cannot  be  produced  profitably  on  the  basis  of  the  "market- 
milk"  price  for  goat's  milk. 

SUMMAEY  AND  CONCLUSIONS 

Roquefort  type  cheese  can  be  manufactured  successfully  from 
goat's  milk,  cow's  milk,  or  mixtures  of  the  two.  Judges  and  pur- 
chasers found  the  goat's-milk  Roquefort  to  be  equal  in  quality  to  the 
imported  cheese. 

The  Roquefort  cheese  process  is  strictly  a  factory  process.  The 
temperature,  humidity,  and  ventilation  of  the  draining,  salting,  and 
curing  rooms  must  be  controlled  accurately.  The  following  procedure 
is  recommended  for  handling  goat's  milk.  (Fresh,  clean  milk  is  nec- 
essary for  a  good  quality  of  cheese.  The  acidity  test  should  be  between 
.16  and  .18  per  cent.) 

Three  or  four  per  cent  of  clean  lactic  starter  is  used  and  three  to 
four  ounces  of  rennet  is  added  at  a  temperature  of  82 °F.  after  an 
acidity  of  .21-22  per  cent  has  been  developed.  The  length  of  time 
of  coagulation  should  be  from  one  to  one  and  one-half  hours.  When 
a  thin  film  of  whey  spreads  over  the  surface,  the  curd  is  cut  two 
ways  with  a  coarse,  vertical  knife  with  wires  from  five-eighths  inch 
to  one  inch  apart. 


20  UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 

Ten  minutes  after  cutting,  the  curd  is  transferred  with  scoops  into 
the  draining  vat.  About  thirty  minutes  after  dipping,  the  curd  and 
mold  are  placed  in  the  hoops,  in  four  or  five  alternating  layers. 

The  cheese  is  turned  several  times  during  the  first  day,  and  twice 
daily  thereafter,  while  in  the  drain  room.  The  hoops  may  be  left  on 
the  cheese  for  one  or  two  days.  The  cheese  remains  in  the  drain  room 
four  or  five  days. 

The  cheeses  are  salted  two  or  three  times  at  two-day  intervals. 
After  from  ten  to  fourteen  days  in  the  salting  room,  they  are  punched 
in  from  twenty  to  fifty  places.  They  are  then  placed  in  the  curing  room 
on  edge  instead  of  flat.  They  remain  in  the  curing  room  for  two  or 
three  months,  and  are  scraped  three  or  four  times.  After  this  period 
they  are  wrapped  in  foil  and  parchment  paper  and  held  for  at  least 
two  months  longer. 

The  average  yield  of  Roquefort  cheese  from  goat's  milk  testing  3.4 
per  cent  butterfat  was  10.34  pounds  for  each  100  pounds  of  milk. 

The  butterfat  losses  in  the  whey  from  goat's  milk  are  excessive. 
These  losses  may  be  decreased  by  adding  about  20  per  cent  of  cow's 
milk. 

Roquefort  cheese  made  from  goat's  milk  is  very  white  in  color, 
similar  to  the  imported  Roquefort  made  from  sheep 's  milk. 

It  is  probably  not  advisable  to  manufacture  goat's-milk  Roquefort 
cheese  if  the  cost  of  production  exceeds  forty  cents  a  pound,  because 
of  the  present  low  wholesale  prices  of  imported  Roquefort. 

ACKNOWLEDGMENTS 

It  was  through  the  close  cooperation  of  the  Bureau  of  Dairying, 
United  States  Department  of  Agriculture,  that  the  development  of  this 
process  in  California  was  possible. 

The  authors  desire  to  express  their  appreciation  to  Professors 
G.  H.  True  and  W.  M.  Regan  of  the  Animal  Husbandry  Division, 
under  whose  direction  the  milk  was  produced ;  to  Mr.  A.  W.  Farrall, 
who  supplied  data  on  refrigeration  and  electricity,  and  to  the  other 
members  of  the  Dairy  Industry  Division  who  gave  helpful  sugges- 
tions. 

LITERATURE  CITED 
i  Matheson,  K.  J. 

1921.      Manufacture   of   cow's-milk   Roquefort   cheese.      U.    S.    Dept.    Agr. 
Bui.  970:1-28. 
2  Marre,  E. 

1906.    Le  Roquefort.    E.  Carrere,  Editeur,  Rodez,  France. 


